2. CONTENTS
Watershed and its importance.
Watershed management and its objectives and
perspectives.
Approach for watershed management.
Geological aspects- natural resources and hazards.
Watershed and drainage patterns.
Individual contributions towards watershed.
3. WATERSHED
A WATERSHED can be defined as a geo-
hydrological unit that drains to a common point by a
system of drains. All lands on earth are a part of
one watershed or another.
The words watershed ,catchment ,basin, drainage
area, are synonymous , and in Indian
usage, pertain to an area and not a line.
The terms micro, mini, sub-watershed or any other
variation of the terms indicate hierarchical division
of the watershed of a stream, river or a drainage
line.
4. IMPORTANCE OF WATERSHEDS
Watersheds sustain life, in more ways than one.
According to the Environmental Protection
Agency, more than $450 billion in
foods, fibre, manufactured goods and tourism
depend on clean, healthy watersheds.
Healthy watersheds are also important for the very
sustenance of human life
5. WATERSHED MANAGEMENT
Watershed management is defined as the process
of formulating and carrying out course of action
involving manipulation of natural, agricultural and
human resources of a watershed to provide
resources that are desired by and are suitable to
the watershed community
The watershed management and exploitation
should not have any adverse effects on soil and
water resources
It is an integrated and multidisciplinary approach.
6. OBJECTIVES OF
WATERSHED MANAGEMENT
Protecting, conserving and improving the land
resources for efficient and sustained production.
Protecting and enhancing water
resources, moderating floods, reducing silting up of
tanks/reserviors, increasing irrigation and
conserving rainwater for crops and thus mitigating
droughts
Utilizing the natural local resources for improving
agriculture and allied occupation of industries so as
to improve socio-economic conditions of local
residents.
7. PERSPECTIVES OF WATERSHED
DEVELOPMENT
HYDROLOGICAL ASPECTS
ENVIRONMENTAL ASPECTS
SOCIO-ECONOMIC ASPECTS
FINANCIAL ASPECTS
ADMINISTRATIVE AND POLITICAL ASPECTS
8. HYDROLOGICAL ASPECTS
Hydrological behaviour of watershed is influenced
by watershed conditions.
The watershed treatment and management
practices alter the slope and roughness
characteristics of the watershed management and
tend to reduce the surface flow and the peak flow
The management practices also reduce the rate
and quantity of the sediment erosion and their
transportation resulting in lower delivery of
sediments into the reservoir
These measure effects flood control, soil moisture
conservation and land use.
9. ENVIRONMENTAL ASPECTS
Development applied locally for developing green
foliage, enriches environment globally in due
course of time.
The local measure of micro-scale watershed
development would have cumulative effect on
environment when considered on a large basin or a
global scale
Reduced onsite erosion and enhance in a well
managed watershed also improve the natural
ecosystem
10. SOCIO-ECONOMIC ASPECTS
In achieving the true objective of watershed
management, the viewpoint of individuals and
communities, who live in the watershed should be
considered.
The socio-economic factors also determine the
motivation of farmers to make necessary
investment of labour and capital in watershed
development.
11. FINANCIAL ASPECTS
The projects can either be fully funded by
government or NGOs or in case of the development
the participating families may be required to
contribute a predefined percentage of cost for
individual works and for community work.
The unit cost for watershed development normally
range from Rs. 4500 to Rs. 6000 per hectare
depending on nature and location of the watershed.
12. ADMINISTRATIVE AND
POLITICAL ASPECTS
Watershed management requires close
collaboration of various planning and implementing
agencies to achieve full benefits of the programme.
Planning should only include those
measures/activities which are acceptable politically.
13. APPROACH FOR
WATERSHED MANAGEMENT
AND DEVELOPMENT
People’s participation is the key to watershed
development programmes.
While the main development activities have to be carried
out by the watershed community itself, the overall
facilitation, coordination and supervision of the whole
programme will be responsibility of a PROJECT
IMPLEMENTATION AGENCY (PIA).
The whole setup for the watershed management follows
a hierarchical approach.
14. ORGANISATIONAL SETUP
District Watershed Development
Advisory Committee
Project Implementation Agency
Watershed Development
Team
Watershed Development
Community
Village Development
committee
15. STEPS FOR PREPARATION OF
INTEGRATED WATERSHED
MANAGEMENT PLAN
Preparation of watershed development plan includes two
main steps:
1. Identification of watershed problems and setting up of
objectives and priorities based on various surveys of
watershed.
2. Formulation of proposed development and
management plan.
16. GEOLOGICAL ASPECTS OF
WATERSHED MANAGEMENT AND
DEVELOPMENT
SOIL
NATURAL
RESOURC WATER
GEOLOGI ES
-CAL
ASPECTS EARTHQUAKES
NATURAL
HAZARDS
FLOODS
LANDSLIDES
17. SOIL
SOIL PROPERTIES: PHYSICAL
SAND SILT CLAY
POROSITY MOSTLY SMALL SMALL
LAGRE PORES PORES
PORES PREDOMINAT PREDOMINAT
E E
PERMEABILI RAPID LOW TO SLOW
TY MODERATE
WATER LIMITED MEDIUM VERY LARGE
HOLDING
CAPACITY
SOIL SMALL MEDIUM VERY LAGE
PARTICLE
SURFACE
18. SOILPROPERTIES:CHEMICAL
VARIES FROOM 0 TO 14
pH (ALKALINE /ACIDIC
/NUETRAL SOILS)
EASILY LEACHED OUT
CHEMICALS (Chlorides and Sulphates,
AND ELEMENTS followed by Calcium,
Sodium, Magnesium and
PRESENT Potassium)
RARELY LEACHED
(Silicates and Oxides of Iron
and Aluminium)
19. WATER
In case of water we consider water quantity and
water quality, where water quantity is imp to
prevent floods and water logging, the concept water
quality is important to delineate the uses for which
water can be used from a given watershed.
20. WATER PROPERTIES:PHYSICAL
Formula: H2O
Density: 1,000.00 kg/m³
Molar mass: 18.0153 g/mol
Boiling point: 99.98° C
Melting point: 0.0° C
21. WATER PROPERTIES: CHEMICAL
Chemically pure water should have only hydrogen
and oxygen.
The water we use for daily purposes has a variety
of other elements like Iron, Magnesium etc. but
these elements should be under permissible limits
prescribed for any purpose like drinking, agriculture
etc.
Water should be of neutral pH, but presence of
certain salts may make it acidic or basic.
22. SOIL AND WATER
CONSERVATION MEASURES FOR
WATERSHED TREATMENT
Soil and water conservation measures to be employed
depend on the purpose for which the land and water is to
be used. There are two broad categories:
1. SOIL AND WATER CONSERVATION MEASURES
FOR AGRICULTURAL LAND.
2. EROSION CONTROL MEASURES FOR NON-
AGRICULTURAL LAND.
23. SOIL AND WATER CONSERVATION
MEASURES FOR AGRICULTURAL LAND
Contour bunding.
Graded bunding or channel terraces.
Bench terracing.
Grassed waterways.
Strip cropping
Mulching
Sub soiling
24. CONTOUR BUNDING
• Contour bunding consists of constructing narrow-based
trapezoidal earthen embankment at intervals along the
contour to impound run off water behind them so that all the
stored water is absorbed gradually into the soil profile for
crop use.
• A series of such bunds divide the area into strips and act as
barrier to the flow of water.
25. GRADED BUNDING
These are constructed where the excess water is to be
removed safely to avoid water stagnation. In these
water flows in graded channel constructed on the
upstream side of the bunds at non erosive velocities
and is led to safe outlets.
26. BENCH-TERRACING
• It is practiced on steep hill slopes ranging from
16-33%.
• Bench terracing which involves converting the
original ground into level step like fields
constructed by half cutting and half filling, helps in
considerably reducing the degree of slope
27. GRASSED WATERWAYS
• These are associated with channel terraces for safe
disposal of concentrated run-off, thereby protecting
the land against rills and gullies.
• A waterway is constructed according to a proper
design and a vegetative cover is established to
protect the channel against erosion because of
concentrated flow.
28. STRIP CROPPING
• Strip cropping consists of a series of alternate strips
of various types of crops laid out so that all tillage
and crop management practices are performed
across the slope or on the contours.
• Strips of erosion –permitting crops are always
separated by strips of close growing or erosion
resisting crops .
29. MULCHING
• Mulching of open land surface in a cropped area is
achieved by spreading stubble trash or any vegetation.
• These are used to minimize splash, to prevent soil from
blowing or being washed away, to reduce
evaporation, to increase infiltration, to control weeds, to
improve soil quality and eventually increase crop yield.
30. SUB-SOILING
• This method consists of breaking with a subsoiler
the hard and impermeable subsoil to conserve
more rain-water by improving physical conditions
of the soil.
31. EROSION CONTROL MEASURES FOR
NON-AGRICULTURAL LAND
Contoured and staggered trenches for hill slopes.
Gully control.
32. CONTOURED AND STAGGERED TRENCHES
• Suitable erosion control in hills
• Adopted for hill slopes >20%
33. GULLY CONTROL STRUCTURE
Gully erosion usually starts as small rills and
then develops into deeper crevices or Ravines
in extreme cases.
it can be controlled by check dams which may
be permanent, semi-permanent or temporary
Temporary check dams are usually made up of
brush wood, wire and poles or loose rocks
Semi-permanent check dams can be earthen
dam, Gabion structure etc.
Permanent check dams are concrete and
masonry structures
36. FLOODS
The management of rainfall and resultant run-off is
very important to control floods and found to
depend on watersheds.
Due to floods, the plains have become silted with
mud and sand that affect the cultivable
lands, watershed management thus helps to reduce
the rate and quantity of the sediment to be
deposited.
The excess runoff from streams during monsoon
can be controlled using techniques like check
dams, percolation dams etc.
This results in mitigation of floods, recharge of
ground water which can be used during times of
drought.
38. EARTHQUAKES
While developing a watershed the zone of hazard in
which the area falls must be kept in mind.
If lineaments such a folds, faults, joints etc. are
more at a place (where watershed is to be
developed) then the area is more earthquake prone
The structures developed must be earthquake
resistant if the area is in a hazardous zone.
39.
40. EARTHQUAKE PREPARATION
The objective of earthquake engineering is to
foresee the impact of earthquakes on buildings and
other structures and to design such structures to
minimize the risk of damage.
Existing structures can be modified by seismic
retrofitting to improve their resistance to
earthquakes.
Emergency management strategies can be
employed by a government or organization to
mitigate risks and prepare for consequences
41. LANDSLIDES
A landslide is a geological phenomenon which
includes a wide range of ground movement, such
as rockfalls, deep failure of slopes and
shallow debris flows.
Although the action of gravity is the primary driving
force for a landslide to occur, there are other
contributing factors affecting the original slope
stability Typically, pre-conditional factors build up
specific sub-surface conditions that make the
area/slope prone to failure, whereas the actual
landslide often requires a trigger before being
released
42. LANDSLIDE PREVENTION
REDUCTION
OF PORE
WATER
PRESSURE
INCREASE
SHEAR
STRENGTH OF
SLIDING SURFACE
CONTROL
WORK PREVENTION
MECHANICAL
OF SOIL
COUNTER-
EROSION
MEASURES
REFORM
SLOPE
PILE
PREVENTIVE
WORK
ANCHOR
43. WATERSHED AND DRAINAGE
PATTERNS
The drainage patterns have effect on watershed
development as they decide the type of
sedimentation processes the quantity of sediments
and water.
The drainage patterns also give idea of lithology
and relief, eg. the development of dendritic to sub
dendritic drainage in the watershed indicates the
area of massive rock types, gently sloping to almost
horizontal terrain and low relief
It has been suggested that the parallel drainage in
Deccan Basalt terrain is initiated due to the step like
nature of the Deccan traps which is joined by
subsequent lateral ravines giving a sub-parallel
pattern (Dhokarikar, 1991)
44. SINCE EVERYONE IS A PART OF
WATERSHED
Don’t pour toxic household chemicals down the
drain; take them to a hazardous waste centre
Recycle yard waste in a compost pile & practice
mulching.
Adopt your watershed.
